Conventional birdhouses are typically fixed in position on posts, trees or houses. These fixed birdhouses are therefore easily accessible to natural predators such as cats. They are also subject to the harsh effects of wind, rain and snow which blow directly into the entry hole much of the time.
Conventional birdhouses are usually poorly ventilated and have little or no provision for drainage. They have an entry hole of a fixed size and therefore attract a limited number of bird species. They usually have a perch which can be utilized as a footing by predators or by troublesome birds to harass or dislodge the occupants.
Conventional birdhouses have an entry hole which is positioned a considerable distance above the bottom of the birdhouse in order to protect the young birds (fledglings) from large predators. However, fledglings have considerable difficulty climbing the inner wall up to the entry hole to make their early learning flights. The inner wall usually is smooth and is difficult to climb. Accordingly, it is a known fact that many weaker fledglings often die prematurely because they are unable to leave the birdhouse.